/// <summary>
/// 保存一个备忘录
/// </summary>
/// <param name="memento"></param>
public void SaveMemento(Memento memento)
{
this.memento = memento;
}
/// <summary>
/// 恢复当前状态为备忘录所保存的状态
/// </summary>
/// <param name="memento"></param>
public void RestoreMemento(Memento memento)
{
this.state = memento.GetState();
}